Probably some high-level aspects would be great at first to get an idea of what's possible, such as refactoring the RESTful API (the sirix-jax-rx maven bundle).

But it's not necessarily programming. I want to publish a website for instance in the future, that would also be awesome, use the system and post bug reports, features you would like to see, any kind of questions... Or just spread some love ;-)

We're using Sedna at work, which is a NoSQL database using XML and XQuery and it's the worst. The major bottleneck in our application is the database not being able to take the hits and taking an insane amount of time to parse and return just a few queries.

And of course, because it doesn't use SQL, we're pretty much stuck using Sedna unless we feel like replacing all that hand-written XQuery.

huh, really? Did you add index-structures? I don't think Sedna is per se slow, but it might depend on the query. Usually most queries can be rewritten either by the XQuery processor or by hand to take indexes and various other optimizations into account. Just keep in mind that XQuery is inherently much more complex than for instance SQL.

However, why stuck on Sedna? BaseX(.org) (several guys I know), Brackit(.org -- BrackitDB ok, they are just like me at an early stage of development, thus no industry ready solution, but a bunch of clever ideas), ExistDB(.org)...

Probably Mark Logic also fits, at least it seems to be the industry leader.

Yoy are using a product, a software ne, but a product indeed. General purpose products like programming languages aren't so effective. If you are going to make system software, the best is to write your core "product free". Start cheap. Fresh.

All those databases, BTW, are thought for encouraging relationships between entities in detriment of transactionality or queriability...is that what do you intent?

Sometimes it just comes to the basics: review those old good data structures that you saw in college and see what you can do. For massive stuff, YAML seems better suited that XML, in my opinion. And to be honest...it depends great,y in what you intent to do,,,,links?